In the Patent Document 1, a hybrid system is described, which hybrid system can output a power output from an internal combustion engine by its operation and a power output from an electric motor by its operation simultaneously or selectively.
In this hybrid system, a mode for selectively performing the operation of the engine and the electric motor and the stop of the operation (hereinafter, this mode may be referred to as—HV mode—) and a mode for performing the operation of the electric motor and the stop of the operation of the engine (hereinafter, this mode may be referred to as—EV mode—) are selectively performed.
In this hybrid system, a power depending on an actual acceleration pedal manipulation amount is output from the hybrid system.
In the hybrid system described in the Patent Document 1, a required hybrid system power value (i.e. a value of the power required as a power output from the hybrid system) is calculated on the basis of the actual acceleration pedal manipulation amount and when the thus calculated required hybrid system power value is smaller than a certain threshold value, the EV mode is selected and on the other hand, when the aforementioned calculated required power value is larger than the aforementioned threshold value, the HV mode is selected.
In this regard, in the hybrid system described in the Patent Document 1, in order to facilitate the selection of the EV mode at the EV mode selection being required (i.e. when it is required that the EV mode is selected), the power output from the hybrid system on the basis of the actual acceleration pedal manipulation amount at the EV mode selection being required is made smaller than that at the HV mode selection being required.